core: Improve the documentation for funnel shifts#154150
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tgross35 wants to merge 3 commits intorust-lang:mainfrom
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core: Improve the documentation for funnel shifts#154150tgross35 wants to merge 3 commits intorust-lang:mainfrom
tgross35 wants to merge 3 commits intorust-lang:mainfrom
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`rhs` is confusing since for the `Shl` and `Shr` traits, that is the name used for the value to shift by (i.e. `self >> rhs`).
It's a bit easier to understand the results of shifts and otherwise bitwise operations when leading zeros are present.
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r? @joboet rustbot has assigned @joboet. Use Why was this reviewer chosen?The reviewer was selected based on:
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Cc @clarfonthey since you requested some of this at #145686 (comment) |
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Output since it's impossible to read the macros: 
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Shorten the summary line, cover shifts by zeros, rotates, and panics in examples, and turn the "Panics" section into a complete sentence.
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Some ascii art I sketched for this but decided to exclude: // high low
// |0x1234 0x5678| <- shift left 12 bits
// \ /
// \--| /
// |0x4567|
// result
//
// high low
// |0x1234 0x5678| -> shift right 12 bits
// \ /
// \ |--/
// |0x2345|
// result |
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| without modifying the original"] | ||
| #[inline(always)] | ||
| pub const fn funnel_shr(self, rhs: Self, n: u32) -> Self { | ||
| pub const fn funnel_shr(self, low: Self, n: u32) -> Self { |
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Personally I think "right" gives a better intuition here than "low". This is about the number as a bitstring after all, not about it's numeric value.
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Change the variable name to make things a bit more clear, then rework funnel shift documentation. Examples now cover shifting by zero and emulating rotates.
Tracking issue: #145686